Influence of clay minerals from lateritic nickel ore in the recovery of this metal.

Author(s)

Eliana Satiko Mano

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Escola Politécnica (EP/BC)
• Defense date: 2013-11-04

Examining board members

Arthur Pinto Chaves; Eldon Azevedo Masini; Reiner Neumann; Sonia Maria Barros de Oliveira; Cyro Takano

• Advisor: Arthur Pinto Chaves; André Sampaio Mexias

Abstract

The nickel lateritic ore from Niquelândia Goiás - is one of the most important and well known Ni lateritic deposits in Brazil. High nickel contents, the deposit dimension and also, their associations with clay minerals are the main reasons for researchers, such as Trescases and Santos, to have studied it in the 1970s. The Cuban and Australian deposits have nickel associated to oxidized ores and serpentine, respectively, but at Niquelandia, nickel is specially associated to smectites and vermiculites. The Caron Process is not the most suitable for treating Ni-bearing clay minerals, as those present in Niquelândia. Consequently, there are many losses related to silicated ore. The reduction temperature used in the Caron process in the reduction step can form minerals, such as pyroxene, amphibole and olivine. These minerals trap Ni inside their structure; hence, the ammoniacal solution can not access this element and solubilize it. The main Ni-bearing clay mineral observed in Niquelândia is smectite. Actually, the silicated ore is composed by a mixture of smectites. One of them is a Ni-trioctahedral one, which is not affected by ammoniacal leaching; however, it has a significant amount of nickel. On the other hand, a dioctahedral Fe-rich smectite, has high Ni recoveries, but its nickel content is lower. Samples composed by a mixture of di and trioctahedrals smectites - Fe-Mg-Ni montmorillonite/stevensite are the most common. Considering all these factors, the losses related to Ni-recoveries can be avoided by a better feed control. The ideal feed should be an oxidized ore + silicate ore composed by dioctahedrals smectites. The Ni trioctahedral smectite should be avoided. (AU)